To date, for most diagnostic assay apparatuses for the detection of small quantities of analytes in fluids, multiple-sample preparation and automated reagent addition devices, or multiple-sample assay apparatuses for identifying a number of samples at the same time, either in parallel or serial procession, have been designed to improve efficiency and reduce costs. Such an automated reagent preparation device and an automated assay apparatus are often integrated into a single thin film type apparatus. This thin film type diagnostic assay apparatus can automatically or semi-automatically accurately analyze in an hour hundreds of analytes using trace amounts of a sample and reagents. The thin film type assay apparatus needs a valve for automatically supplying a sample or reagents (enzyme and buffer). However, designing such a valve for a thin film type assay apparatus is complicated. Therefore, there is a need to design a simple, thin film valve suitable for the thin film type assay apparatus.
For a CD and a DVD as a thin film substrate, a standard CD is formed from, for example, a 12 cm-polycarbonate substrate, a reflective metal layer and a protective lacquer coating. The format of a DVD, a CD, and a CD-ROM are described in the ISO 9660. The polycarbonate substrate is an optical-quality transparent polycarbonate substrate. A data layer in a DVD and a CD may be part of a polycarbonate substrate and data can be engraved in the form of a series of pits by a stamper in an injection molding process. The stamping master is mainly glass. Such a polycarbonate substrate may be modified as a thin film type diagnostic assay apparatus, such as a bio-disc, which detects a trace amount of a material in a fluid. In this case, in the injection molding process, instead of the pits, channels as fluid flow paths and chambers as buffer reservoirs may be formed, in a surface of the disc. Additionally, a thin film type valve that can smoothly control the flow and flow rate of the fluid through the channels formed in the thin film type disc is required.
Hereinafter, a diagnostic lab-on-a-chip detecting a trace amount of a material in a fluid, a disc in which thin film valves are integrated along with a bio chip such as a protein chip and a DNA chip, and a diagnostic disc in which thin film valves are integrated and biological and chemical processes are performed to detect a trace amount of a material in a fluid, are collectively called a “bio-disc” or “thin film valve device”, wherein these devices are manufactured by modifying a common disc, such as a CD-ROM, a DVD, and the like.
A device for flowing a fluidic sample that is injected into an injection hole of the disc in a surface of the disc using the centrifugal force and a device for flowing a fluidic sample that is injected into an injection hole of the disc into a channel and a chamber using the centrifugal force to separate the sample are widely known. However, these devices could not overcome a difficulty of constructing a thin film type structure, and thus do not ensure precise control of the flow rate.
A general valve using an electromagnet opens or closes a channel using a cylinder or a plunger that is moved due to a magnetic force. To intensify the magnetic force so as to move the cylinder or plunger, a ferroelectric core of an appropriate size and a number of wires wound around the core are required. Also, a large amount of electricity is required to turn on or off the valve and move the cylinder or plunger. The valve using the electromagnet cannot be constructed as a thin film type valve due to the size of the electromagnet. The valve generates excess heat as a result of consuming a large amount of electricity. Thus, the valve is not suitable to be a thin film valve
To address these problems, in an embodiment of the inventive concept, valves are opened using the centrifugal force generated as the thin film valve device rotates, in addition to using the heat generated from a heat generating apparatus. As a result, the volume of external magnets is reduced, and the reliability of opening the valves is ensured. In addition, the fluid does not contact the valves as holes, instead of channels, are opened. Thus, the properties of the fluid are less likely to be changed as the heat is generated.
A bio-disc is required to store liquid-phase materials in a chamber to be stable throughout the period of circulation. However, the body of the bio-disc shrinks and expands for a long period of circulation due to environmental factors such as temperature, which may lead to a gap in the valve. As a result, the fluid stored in the chamber evaporates through the gap in the valve, which lowers the reliability of sealing of the valve. To solve this problem, an embodiment of the inventive concept provides a thin film valve device that closes and opens the hole as follows. A bead (ball) stopple, a nonmagnetic stopple, a magnetic stopple, or a heat shrinkable stopple, which are coated with an adhesive (a gluing agent), or a thin film adhesive tape is attached to the hole to tightly close the hole for the period of circulation. In addition, when opening the hole, the adhesive strength (binding force) of the adhesive is lowered using the heat generated from the heat generating apparatus, and then the bead (ball) stopple, the nonmagnetic stopple, the magnetic stopple, the heat shrinkable stopple, or the thin film adhesive tape is separated from the hole using the hydraulic force of the fluid, which is generated due to the centrifugal force.
Hereinafter, the bead (ball) stopple, the nonmagnetic stopple, the magnetic stopple, the heat shrinkable stopple, and a hole closing film formed by the thin film adhesive tape, which are used to open and close the hole, are collectively referred to as thin film valves.
The thin film valves are formed as thin films. In addition, the adhesive used as a coating agent for the thin film valves is flexible to adapt to the expansion and shrinking of the body of the thin film valve device according to environmental factors such as temperature, thereby preventing the problem of sealing, which is caused due to the expansion and shrinking of the body, during the period of circulation.
A thin film valve device according to an embodiment of the inventive concept includes valves in the form of thin films. In addition, a larger number of valves may be integrated in a unit area. Thus, the thin film valve device is applicable in constructing valves for a thin film diagnostic device, such as a lab-on-a-chip or a DNA chip, which can detect a trace amount of a material in a fluid. For example, the thin film valve device is applicable in constructing a valve device by modifying a common disc device, such as a CD-ROM, a DVD, and the like, to open and close a channel and a hole in the body of the thin film valve device or to control the flow rate of a fluid.